Cable clamp



April 29, 1930. c. A. JOHNSON CABLE CLAMP Filed Feb. 23, 1926 ber.

' *9 taken on the 111192 201. a-

' Patented Apr. 29, 1930 VIUEQHTFED m am ethics orrns'rnn A. JoHNsoi o oI IoAGo, ILLINOIS, ssienoaroinnrnnson ELECTRIC COMPAATYi or CHICAGO, ILLIn-oIs, A'CORPORATIO1\T.OF ILLINOIS i ;Application filedFebruary 23, 1926. Serial no. 89,852.

d This invention relates to cable clamping means for outlet boxes, junction boxes,-switch boxesand the like.

The use of. armored cable for electric wira ing necessitates the. employment of a bush I a knock-out hole in the box into which itmay be inserted.

' The present invention aims to providecable receiving boxes {with a device capable of V '15' clamping a" conduit or cable and ofbushing the opening in the. end of the cable; which in additionserves as an abutment for the end of the cable; which can be loosely contained in the box in assembledrelation without dan- 2 ger of-being rattled apart; which need not be Wholly removed'from-the boxi'n order to of bills lnvention is not necessarily effected {be disassembled; and which comprises a screw actuated clamping member and a bushing element mounted on the clamping mem- In'the accompanying drawings I have illustrated an exemplary and the preferred form of the invention asapplied to a switch box but it is to be understood that thejde- 7 vice in detailsof'construction and arrangement of parts may be varied'to adapt it to other-types of boxes. This will appear from i the character of the invention as hereinafter described and by the 500136 0]? the appended ''claims. 1

' In the draWings,"Figure'l shows a front a wall switch boxreceiving two 7 1 of the devlce of. the present Invention sone elevation of armored cables on the upper face. v I.

Fig. 2 is a cross section ofth switch box Fig. 3 is a cross section of the box taken on'the line 3 3i )f Fig. 2.

Fig. 4 is a cross section of. the boxtaken on 45 the'line 44 of'Fig. 2, showing the device in elevation viewed from below.

, Fig. 5' is a-viewshowing in ffulllines'the parts in loose relation in the absence of cable,

and in. dotted linesin disassembling position.

" 5o Figs. 6 and ,7, are detailed. illustrations: of

tively. I o

In the drawings the box employed to receive the cables is represented by a well' known type of switch box 10 which is proabout'the rear portion of the box. Inthe present lnstance the box is shown as receiV- ing two cables 12 and 13 entering the box at the topside thereof throughopenings 14 pro- 'ducedby removing the knock-outs 11 there.- jfrompIn the present instance the cable shown has a spiral groove 15 therein, the sides "of-which serve to span one edge of the hole 14, as indicated at 16 (Fig. 2) thus to aid in holding the cable longitudinally fixed.

" the bushing plateand clamping yoke, respec -vided with knock-outs 11' variously disposed However,'it is to be'understood that this groovedtype of cable is not necessary to the proper'operation of the device, a smooth ca- 'ble or conduit being-equally suitable.

The clamping of the cable by the device bythe engagement of the groove with-the edge ofthe hole; The invention provides -means Within the box toiproduoe'fp ressure' upon one side of the cable to'pinch or bind it-against a rearward portion, this being the 'edgeof the hole in "the present instanceJ A pressure producing 'means is illustrated by the yoke l'l havingtwo wings .18 and 19, one foreach of the'twoI cables. A screw 20 passes through a hole' 21 in the yoke andenters the rear face of the box at 22. The width of the yoke andits location is preferably such that itmoves along'the top face of'the box through which the cables enter."

The hole-bushing member forming part to be mounted upon thejclamping yoke but is not necessarily movable therewith as the latter is drawn't'o the rear-of the box for clamping the cables. The main] object in mounting the bushing memberis to permit,

the clamping yoke to be movedinto' clamp-5 ing position While the bushing member remainsstationary. I The mount ng of the bushing member on the yoke is so accomplished that it cannot fall away from the yoke when loosely positioned in the box in the absence of cable, and so that it is always in operative position in spite of any rough handling to whichthe boxmay be subjected to,produce rattli-Iigof {the loosely momi'tedjparts.

In the present instance the bushing member comprises a fiat plate 23 positioned beiofwttheaabeve described yib'ke 17 "The: bushagainst the rear face of the box, thus to determine its position. The bushing plate holes 25 smaller than .theend openings of the cable, the holes being spaced apart a suitahle-.di stanee-to accemmedateitheI-twoadjacent cables '12 and I3. Furthermore th e holes are offset toward the-rearIof-the box -;sothat they are not concentric with the knock-out openings letthrough which-the caable enters. 'l he reason fonthis is; beeause the knock-out openingisusually considerably larger than-the cable employed and the; plate is -adapted to -be I positioned concentrically with the-enteringcable rather thana hole through which; the cable enters. in order hettertogserve its purpose as a hushi'ng plate,

thaperipheries of the-lholesi25 are-rounded as -i126 andthematerial of the-platefabout' therhole serves as-;a$st0p or abutment 27 for the end tithe cap-1e. By 3 this constr letio'n the cable is-insertd, sothat it Iabnts-the plate and the portions-of the wires 28 projecting f rom the cable-thus bear against- 'the:rounded was edge 26 andare prevented 'i-rom being eiit by thesharp edge oiflthecahle -armor-. p p

, -T-he bushing plate 123 is provide'd with a construction which permits itto beheld loosely and movablymounted onthe yoke li yet capable of being stationa'rily positioned withinthe-box in suh a manner'that/Jthe yoke is ermitte'd to move \for a clamping purpose's.

arious constructions may-- he employed 5 to secure result bllt; preferably the; plate :28

is recessed forming: a-c'entrah elongated V -transv;erse;slot 29 betweei rthei two holes r25. -The. 'elamping --mem -ber is j provided with r a part-cooperating with the-recessed plate for mo untings the plate and for-retainingit in all itgorwardrpositiens of-the clamping; member.

S19E29areew related thatthepartscan be po A .sit ioned for separation; .The ;preferred ar- 1: ngement is to provide=a :Sl'llflplB slot: 219 and 5a Tehaped lug-haviif ga legorrstemportion :31; whic his c-apable of turnig? within :the slot ing member has an edge 24-- normal-1y: lying "said plate having holes therein v end openings of the cable and the plateserving'as an abutment for said ends,

mount thefpl-ateionz the rotated-about the T -leg 3 1-'a quarter turn to allew the retaining nee-lea member 32 of the T to lie parallel with the slot 29. Thus the'piate and yoke are positioned for separation without removing the screw from the boX. The corners ofthe plate 23 are cut ofi to facilitate} turning by shorteningthe diagonal length; -However, the screw in the above position is preferably just ienterecl into the Walls of the-box so that on 'further entering thescrew toinovethe yekerearwardlythe I 3plate'23 is oarried sitfliciently forward to prevent the above described quarter turn, thereby preventing remov'aloi the platexfro'm the yoke, and also removing. any chance that they. become rattled out" of cooperating relation. normally assembling the device with the screw suficiently enteredtoprevent this turn,\the parts are held alwaysinoperative relation such that f they cannot be displaced without retracting the screwi :I claimas my invention: 1

cable-clamp fora box having fcabl'e 'receiving openings thereinin one wallzad- .jacent another wall of the box comprising, in combination,'-a yoke slidablealong-the first walk toward the. second wall t-rscrew tof draw said yoke toward-thesecond wall to=iclamp cables entering-said holes, .aplate. carried. on

, saidgyoke having an edge-against said second wall, sald plate havlng a transverse slot therein and a' lug on the yoke 'slidable insaid slot,

said. plate havirng-bnshii g holes therein positioned tobush: the. ends of cables ezlamped-by said yoke. r I

2. cable clamp adapted for-use in con-3; unction with 'a. "box having cab-le receiving openings; therein infone wall, comprising, in

. combination ayoke having two side'wings for adjacent cables, a screw-passingthrough/an aperture in said yoke and into thread-eden- .gagement with the 2 adjacent bex wall for drawing: said yoketo the box wall for clamp ing the cables, a plate carried on the yoke adapted to have an edge lie against the wall, to bush the I and coop erating means ontheiplate and yoke to re- =rainitheplateon the yokean'd to permit "transverse motion of the yokeiwith' respect to 1 the plate. I

=3. cable tlamp ada ted for u con- 'L 1: *tlenwith wall 'eomprising,in combinatmn; a yeke having twoside wings i for N iadgacenticwbles, screw for drawing 'said yoke to the box wall for clamping the cables,

ing of the plate without demounting the de-' vice from the wall of the box.

, l. A cable clamping device for outlet boxes and the like comprising, in combination, a clamping member arranged to be dr'awntoward a wall of a box to clamp a cable entering said box, a screw passing through an aperture in said member and into screw threaded engagement with said wall, a bushing element adapted to bush such a cable, and means connecting said bushing element slidably on said member to permit said clamping memher to be drawn toward the wall to clamp the cable, a portion of said element being arranged normally to abut said wall of the box. 5. In combination, a box, a plate having two bushing'holes therein at the ends, thereof and a central elongated slot between the holes transversely of the plate, a clamping-yoke mounted formotion parallel to the plane of off the lug when theplate is tipped with respect to the wall, and a screw passing through an aperture in said yoke and into threaded en- 8. In combination, a box having cable re- 'ceiving apertures in a wall thereof, a plate positioned parallel to said wall and having two bushing holes therein substantially alined with-said apertures, a clamping yoke mounted for ."movement parallel to and transversely ofthe; plate, interengaging means on said plate and yoke arranged to connect the plate to the yoke when the plate is parallel to said walland to permit the plate to be disengaged from the yoke when tipped relative to said wall, and a screw passing throughan aperture in said yoke and into threaded engagement with the wall of'the box for drawing the ciently long to permit said plate to be tipped with respect to the yoke to permit the plate i to bedisengagedfrom the yoke without dis engaging the screw from the box.

' In testimony whereof, I have hereunto af-' fixed my signature cnnsrn'n A) JOHNSON.

the plate andtransversely of the plate, a lug 1 on said plate enteringsaid elongated-slot, retaining means on said lug extending over the sides of the slot, and a screw positioned parallel to the slot for drawing the yoke toe ward the wall of the box, said plate having an I edge arranged to abut said wall, the slot permitting movement of the yoke. i

6. In combination, a box having a hole for a cable, a bushing plate positioned opposite to said hole to serve as a. stop for the end of the cable,said plate being arranged to abut a wall of thebox andhaving a slot therein perpendicular to said wall, a clamping yoke movable along one side of the plate between i the plate and projecting into said slot and hooked over the edge thereof to retain the plate and yoke together, and a screw to draw the yoke toward said wall of the boxto clamp the cable entering the cable hole ofthe box.

In combination, a box having cable receiving apertures in a wall thereof, a plate the box hole, a lug on said yoke positioned parallel to said wall and having two bushing holes therein substantially alined with said apertures and a transverse elongated slot therebetween, a clamping yoke mounted for movement parallel to and transversely of the plate, a lug on said plate slidable in said slot and having retaining means extending over the sides of the slot to hold the plate to the yoke when the plate isparallel to said wall and to permit the plate to be slid i yiike toward the wall, said screw being suffi- -r 

